Rod mill



Sept. 4, 1956 o. G. RICHARDSON ROD MILL 2 Sheets-Sheet 1 Filed Jan. 19,1954 R m w W.

wmflmmz am I ATTOK/VEYJ Patented Sept. 4, 1956 ROD MILL Orpha G.Richardson, Fresno, Calif. Application January 19, 1954, Serial No.404,905 1 Claim. (Cl. 241-179) This invention relates to rod mills andmore particularly to a rod mill having drum carried rods or rollers andfree rods or other impact elements, cooperating with the drum carriedrollers to provide a grinding action.

It is among the objects of the invention .to provide an improved rodmill having a drum supported for rotation about a substantiallyhorizontal axis and having an inlet structure at one end and an overflowoutlet structure at the other end of the drum; in which the drumincludes a cylinder, head plates and end plates disposed at therespectively opposite ends of the cylinder, stay rods disposed againstthe outer surface of the cylinder at angular intervals therearoundholding the head plates and end plates in position at the respectivelyopposite ends of the cylinder, and rollers disposed around the innersurface of the cylinder and journaled at their ends on the head plates;in which material pulverized by the mill is discharged through the endplates at both ends of the drum; in which either rods, balls or pebblesmay be used in the drum as the material crushing elements; in which theend plates or grizzly plates are provided with apertures determining theparticle size of the material discharged from the mill; which includes asufiicient number of separable parts to render the several parts lightin weight and of small size compared to the parts of similar mills ofcorresponding capacity now in use so that the parts of the mill can beconveniently transported to mining locations that are remote and ofdifiicult access; which includes parts that can be easily assembledtogether by a single mechanic in a short time to provide the completemill; and which is simple and durable in construction, economical tomanufacture, and efiicient and efiective in operation.

Other objects and advantages will become apparent from a considerationof the following description and the appended claim in conjunction withthe accompanying drawings wherein:

Figure 1 is an end elevational view of the mill at the overflow outletend of the mill;

Figure 2 is a fragmentary end elevational view of the inlet end of themill;

Figure 3 is a longitudinal cross sectional view on the line 33 of Figurel; and

Figure 4 is a transverse cross sectional view on the line 44 of Figure3.

With continued reference to the drawings, the mill comprises a drum,generally indicated at 10, cylindrcial sleeves 11 and 12 projecting onefrom each end of the drum coaxially of the drum and providing bearingarbors outwardly of the corresponding ends of the drum, journal bearings13 and 14 receiving the sleeves 11 and 12 respectively outwardly of thecorresponding ends of the drum and rotatably supporting the sleeves forrotation of the sleeves and the drum about a substantially horizontalaxis coincident with the longitudinal center line of the drum andsleeves, suitable pedestals or supports 15 and 16 respectivelysupporting the bearings 13 and 14, driving means, generally indicated at17, for rotating the drum, and a feed scoop 18 mounted on the distal endof the inlet sleeve 11.

The drum 10 comprises a steel cylinder orbarrel 20 of suitable size andwall thickness, a mill capable of pulverizing approximately one ton ofore in an hour having a cylinder of approximately 30 inches diameter, 40inches length and a wall thickness of approximately one-quarter inch.Grizzly plates 21 and 22, in the form of steel disks of circular shapeare disposed one against each end of the drum in closing relationship tothe corresponding ends of the drum. These plates have centrallydisposed, circular openings 23 and 24 and have a diameter somewhatgreater than the external diameter of the drum 20 so that the marginalportion thereof projects outwardly beyond the outer surface of the drum.The plates 21 and 22 are provided, each with a circular series ofangularly spaced apart apertures extending around the outer surface ofthe drum 20 and stay rods 25 extend longitudinally of the drum incontact with the outer surface of the drum and at substantially equalangular intervals around the drum and extend through correspondingapertures in the plates Hand 22. The end portions of the stay rods 25are screw threaded and nuts, as indicated at 26 and 27 are threaded ontothe respectively opposite end portions of the stay rods and bear againstthe outer side of the plates 21 and 22 respectively to hold these.plates firmly against the corresponding ends of the cylinder 20 and influid sealing engagement with the ends of the cylinder.

Header plates 28 and 29 are disposed one at each end of the cylinder 20in spaced and substantially parallel relationship to the correspondinggrizzly plates 21 and 22. The header plates 28 and 29 are each providedwith a circular series of apertures receiving the corresponding ends ofthe stay rods 25 and nuts, as indicated at '30 and 31, are threaded ontothe stay rods at the outer side of the header plates 28 and 29respectively to force these header plates against the outer ends of thecorresponding nuts 26 and 27 which serve as spacers to maintain theheader plates spaced from the outer surfaces of the correspondinggrizzly plates. The header plates 28 aud 29 are provided with centrallydisposed openings 33 and 34 respectively and domed heads 35 and 36 aresecured at their open ends to the outer sides of the header plates 28and 29 respectively coaxially of these plates. The domed heads 35 and 36are hollow steel bodies of hemispherical or hemispheroidal shape and areprovided with centrally disposed openings 37 and 38.

The inlet sleeve 11 extends through the central openings in the domedhead 35, the header plate 28 and the grizzly plate 21 and is rigidlysecured to the head 35 and header plate 28 by being welded thereto butis left free of the grizzly plate 21 so that the grizzly plate can bechanged, when desired. It will be evident that the domed heads 35 and 36braces the respective header plates 28 and 29 and forms a supporttherefor.

The outlet overflow sleeve 12, which is of larger diameter than theinlet sleeve 11, extends through the central apertures in the head 36,the header plate 29 and the grizzly plate 22 and is rigidly secured tothe head 36 and header plate 29.

Cylindrically shaped rollers 40, of specially hard metal alloy aredisposed Within the cylinder 20 and extend longitudinally of thecylinder at substantially equal angular intervals around the innersurface of the cylinder. The grizzly plates 21 and 22 are providedrespectively with circular series of angularly spaced apart holes withinthe corresponding ends of the cylinder 20 and arbor pins, as indicatedat 41, are journaled one in each aperture in the inner series of holesin the grizzly plate 21 and are inserted in coaxially disposed recessesin the adjacent ends of the rollers 40. Arbor pins 42 are journaled onein each of the holes of the inner series of holes in the grizzly plate22 and each of these pins 42 is received at one end in a coaxiallydisposed recess in a corresponding roller 40. The arbor pins 41 and 42rotatably mount the rollers 40 on the grizzly plates 21 and 22 inposition such that the rollers are slightly spaced from the innersurface of the cylinder 20 and are free to rotate about their ownlongitudinal center lines as axes. A spacing between the inner surfaceof the cylinder and the adjacent surface portions of the rollers ofapproximately one-eighth of an inch has been found to provide entirelysatisfactory results in use.

Each grizzly plate is provided with a circular series of patches ofsmallperforations within the correspond ing end of the cylinder 20, eachpatch of perforations being disposed between two adjacent holes of thecircular series of holes or apertures receiving the corresponding arborpins 41 and 42 and the apertures being of a selected size to determinethe particle size of the material discharged from the mill. Eachaperture of the series 43 in the grizzly plate 21 and of thecorresponding series in the grizzly plate 22 tapers somewhat from theouter to the inner surface of the corresponding grizzly plate so thatpulverized particles of ore passing through these apertures will nottend to stick or jam in the apertures but will be washed freely throughthe apertures by the water intrained with the crude or unpulverized orefed to the mill. The pulverized material discharged through theperforations in the grizzly plates at the respectively opposite ends ofthe drum cylinder 20 is discharged through the space between the grizzlyplates and the adjacent end or header plates 28 and 29 and falls into asuitable receptacle 44 disposed below the drum of the mill.

Material crushing elements, as indicated at 46, 47 and 48 are freelydisposed in the space within the cylinder 20 surrounded by the rollers40, these elements being illustrated as heavy rods although otherelements, such as tubes or balls can be used with advantage underdifferent operating conditions of the mill. When the drum is rotated theelements 46, 47 and 48 are carried upwardly on the rollers 40,centrifugal force causing these elements to stick to the inner side ofthe drum structure until the elements are raised to a position in theupper half of the space within the drum, whereupon the gravity of theelements overcomes the centrifugal force acting thereon and the elementsfall to the bottom of the drum crushing material in the drum on therollers 40. Because of their free rotation in the drum the rollers willbe equally worn on all sides and will not be subjected to excessive wearwhich will necessitate their replacement at frequent intervals duringthe use of the mill. Also, because of this freely rotatable mounting ofthe rollers the rollers will roll under the material crushing elementsand the material will be crushed into substantially precise particleswithout the production of slime or sludge such as is produced by slidingaction of the crushing elements on the rods usually provided in suchmills and fixed relative to the drum. The spacing between the rollersand the inner surface of the drum provides for the washing of the orematerial in the drum freely from the inner surface of the drum so thatall of the ore fed to the drum is rapidly crushed to desired particlesize and discharged from the drum through the perforated grizzly platesat the ends of the drum. The drum will not become overloaded regardlessof any excess of the intake rate over the discharge rate of thepulverized ma terial since any excess material in the drum will bedischarged through the overflow discharge sleeve 12 and,

if desired, this overflow material can be returned by suitable means tothe inlet end of the drum to be fed back into the drum.

nnular spur gear 50 is disposed in surrounding An relationship to thedomed head 36 of the drum and is rigidly secured to the head 36coaxially of the drum so that the domed head 36 defines a mounting forgear 50. Suitable bearing pillows 51 and 52 are mounted on the top ofthe pedestal 16 in spaced apart relationship to each otherlongitudinally of the axis of the drum and a drive shaft 53 is journaledin these hearings. A spur gear 55, smaller than the gear 50, is mountedon one end of the drive shaft 53 and meshes with the gear and a suitablepower plant is connected to the shaft 53 to rotate the spur gear 55 andturn the gear 50 and the drum 10 at a speed less than the rotationalspeed of the shaft 53.

A right angular scoop or dipper 57 is mounted on the distal end of theinlet sleeve 11 at the outer end of the bearing 13 and projects radiallyfrom the sleeve and also tangently of the sleeve to dip or scoop up amixture of material to be crushed and water from a suitable tank orhopper into which the dipper dips as the drum is rotated. A spiral ribor vane 53 extends through the interior of the feed sleeve 11 and aroundthe inner surface of the feed sleeve to insure a uniform feed of themixture of water and ore or other material to be pulverized, into thedrum of the mill.

The particle size of the crushed material discharged from the mill canbe varied by using different grizzly plates having correspondinglydifferent size perforations therein, the rate of discharge can becontrolled by the number of perforations in the grizzly plates and, ifdesired, one perforated grizzly plate can be replaced by a grizzly platewithout the perforations 43 so that the discharge will take plate at oneend of the drum. Alternatively, both of the grizzly plates can beomitted and the corresponding header plates secured directly against theadjacent end of the drum to provide a center discharge mill dischargingat one end only through the outlet overflow sleeve 12. In this case therollers 40 would also be omitted and the material crushed directlyagainst the inner surface of the wall of the drum.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is, therefore, to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claim rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claim are, therefore, intended to be embracedtherein.

What is claimed is:

A rod mill comprising a drum mounted for rotation about its axis andhaving an inlet sleeve and an outlet overflow sleeve extending coaxiallytherefrom at respective opposite ends thereof, power driving meansoperatively connected to said drum adjacent one end thereof forimparting rotation thereto, material crushing means disposed within saiddrum for movement therewithin, said drum comprising a barrel, perforatedgrizzly plates disposed one against each end of said barrel in closingrelation thereto, header plates disposed one at each end of said drum,means securing said grizzly plates and said header plates to said barrelwith said header plates spaced from the outer sides of the adjacentgrizzly plates to provide discharge spaces for pulverized materialflowing from the interior of said barrel through said perforated grizzlyplates, and dome-shaped heads secured at their open ends to each of saidheader plates and having centrally disposed openings thereinrespectively receiving said sleeves to reinforce the connections betweensaid sleeves and drum and to provide braces for the respective headerplates, one of said dome-shaped heads defining a gear mounting, saidpower driving means including a gear mounted on said one dome shapedhead.

References Cited the file of this patent UNITED STATES PATENTS 939,044Lindhard Nov. 2, 1909 1,275,184 Fairchild Aug. 6, 1918 2,478,467 DoreAug. 9, 1949

